From owner-freebsd-current@FreeBSD.ORG Wed Jul 25 14:49:01 2012 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 4B587106566B for ; Wed, 25 Jul 2012 14:49:01 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-lb0-f182.google.com (mail-lb0-f182.google.com [209.85.217.182]) by mx1.freebsd.org (Postfix) with ESMTP id B816C8FC0A for ; Wed, 25 Jul 2012 14:49:00 +0000 (UTC) Received: by lbon10 with SMTP id n10so862591lbo.13 for ; Wed, 25 Jul 2012 07:48:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=V59hpLROxBClv+EqUt821Vnfp4hmAzfpgX1m2HYMql0=; b=haky0VUI4sO/28nrzpwv+WEUPichies+0DXVeuuc93gEID5AwMjstliLDu3dwcDkSB c/UOcmHp+dTeuf3FqQ0VgQHEOENvAyRgs1VcX4/eVKLdz2T4h3OjJ3nNJVmL2G5g7wtK yed5QLeMxnqBbj4uQ0pPST+qed1oPKD4/gL5V1ySvUv4sFcmAkfNjuApOBklsOWhfvkD RvvnMtaZBKMmozuJHGYLq0iWTjO9O+B5xuuci2pYHp1t8Oa2PQYvLaTFMzGFu2l8fRck bGIRfyKWqnm8ESS3cL/3LHJCRg+rmZHyWZ8ze5kRo1lQw9+8n0t4WeUK6hy2bGWek3jB t5rw== MIME-Version: 1.0 Received: by 10.112.27.226 with SMTP id w2mr11950891lbg.57.1343227737820; Wed, 25 Jul 2012 07:48:57 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.112.20.197 with HTTP; Wed, 25 Jul 2012 07:48:57 -0700 (PDT) In-Reply-To: <20120724202019.GA22927@onelab2.iet.unipi.it> References: <20120724202019.GA22927@onelab2.iet.unipi.it> Date: Wed, 25 Jul 2012 07:48:57 -0700 X-Google-Sender-Auth: MYnZOa5x5LAN0owgqqAGd9Fp53c Message-ID: From: Adrian Chadd To: Luigi Rizzo Content-Type: text/plain; charset=ISO-8859-1 Cc: current@freebsd.org Subject: Re: RFC: use EM_LEGACY_IRQ in if_lem.c ? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Jul 2012 14:49:01 -0000 On 24 July 2012 13:20, Luigi Rizzo wrote: > if_lem.c ("lem", one of the e1000 drivers) has 2 possible interrupt modes: > EM_LEGACY_IRQ uses the standard dispatch mechanism, whereas > FAST_INTR has a custom handler that signals a taskqueue to do the job. > > I have no idea which actual hardware uses it (all of my Intel 1G > cards use either "em" or "igb"), but "lem" is the driver used in > qemu, and there the EM_LEGACY_IRQ gives approx 10% higher packet > rates than the other. > > Any objections if i change the default to EM_LEGACY_IRQ ? I suggest doing some digging to understand why. I bet we all know the answer, but it would be nice to have it documented and investigated. I bet em(4) isn't the only device that would benefit from this? 2c, Adrian